Pteridium species

NOTE: This page Last Updated 01 January 2024

According to current taxonomy, Pteridum aquilinum is retained as a species of Europe, and does not occur in the Americas.
The American Brackens have what is called the Latiusculum morphology, and at least five years ago some taxonomists in the Americas began using Pteridium latiusculum for the American Brackens. Other taxonomists have gone further, and raised the sub-species of the Americas to species rank. However, based on my lengthy review of iNat observations, it is apparent that at least two taxa blend seamlessly together across zones of introgression, namely Pteridium latiusculum latiusculum and Pteridium latiusculum pseudocaudatum.
Old Taxonomy........................................................conjectured New Taxonomy
Pteridium aquilinum feei ...............................Pteridium latiuscuum feei
Pteridium aquilinum latiusculum ................Pteridium latiusculum latiusculum
Pteridium aquilinum pseudocaudatum......Pteridium latiusculum pseudocaudatum
Pteridium aquilinum pubescens ..................Pteridium latiusculum pubescens

It seems likely at some point in time that iNat will implement a new taxonomy of Pteridium.
If you have an observation of Pteridium in the Americas, and it does not as yet have a varietal or subspecies rank, it would perhaps be wise to pursue its identification further.

A recent, worldwide study of Pteridium: https://bsapubs.onlinelibrary.wiley.com/doi/pdf/10.1002/ajb2.1365

GOALS of this journal page/project:

  • For each species of Pteridium listed by Plants Of the World Online (POWO) [https://powo.science.kew.org/taxon/urn:lsid:ipni.org:names:17210050-1#children], provide at least one link to an iNat observation that is "iconic" (in some way) for that species.

  • Review details of said observations, and deduce diagnostic morphological traits for the identification of each species.
    No doubt, knowing where the fern was observed will greatly assist in its identification.
    - - -

Pteridium aquilinum aquilinum [Western Europe], diploid, 2n

Pteridium arachnoideum [South America, Centra America, Mexico], diploid, 2n

Pteridium brownseyi

  • no iNat observations yet (06 July 2023)
    - - -

Pteridium aquilinum capense [South Africa], diploid, 2n

Pteridium caudatum
The original illustration:** https://www.flickr.com/photos/biodivlibrary/16089999985/
Not the airy fern of Central Florida that has of late been called Pteridium caudatum, for it is in fact Pteridium rostratum (see below).

Pteridium central-africanum [Central Africa, of course]

Pteridium aquilinum decompositum [Hawaii], diploid, 2n

Pteridium esculentum [Tropical & Subtropical: Asia -> Australia -> South America], diploid, 2n

Pteridium falcatum

Pteridium latiusculum feei [Mexico], diploid, 2n

Pteridium latiusculum japonicum [Japan, Southeast Asia], diploid, 2n
[Notes: latiusculum morphology]

Pteridium latiusculum latiusculum [Eastern North America; replaced along the American Gulf Coast and Southeast Atlantic by Pteridium latiusculum pseudocaudatum; a look-alike in Southeast Asia and Japan is Pteridium latiusculum japonicum = Pteridium japonicum ] diploid, 2n

ASIDE: iNat has recently coined the common name of "Western Brackenfern" for this species. Well, "Western Brackenfern" occurs in Eastern North America and in Eastern Asia. So this common name is bound to cause a lot of confusion. [EDIT: 21 November 2023: gcwarbler reported that, after reading this "Aside", he took action and removed the iNat Common Name for Pteridium latiusculum. Now, at least, there will be less confusion regrading this species. Thank you gcwarbler. EDIT 16 November 2023: With incessant insouciant inanity, curators of iNat have resurrected the abominably confusing common name of Western Bracken Fern. Weary am I, indeed.]

Pteridium lineare

Pteridium latiusculum pinetorum

Pteridium latiusculum pseudocaudatum [primarily Coastal Plains and near-shore of Southeastern North America], diploid, 2n

Pteridium latiusculum pubescens [Western North America], diploid, 2n

Pteridium revolutum [Subtropical & Tropical Asia & India to NE Australia]. diploid, 2n
synonym, Pteridium aquilinum wightianum
https://www.inaturalist.org/observations/197064936 - 2 photos
https://www.inaturalist.org/observations/195082730 - 8 photos
https://www.inaturalist.org/observations/193790491 - 4 photos
[Notes: when young/small, a resemblance to Pteridium aquilinum of western Europe. However, when large mature fronds are produced, they resemble Pteridium arachnoideum in having a winged rachis, long terminal lobes, and sub-leaflets with long lateral lobes near perpendicular to the mid-vein]

Pteridium rostratum [south peninsular Asia through Malaysia to Eastern Australia - and Central Florida], tetraploid, 4n
synonym,Pteridium semihastatum

Pteridium yunnanense

My perception of life forms
is that what we think of as separate species
are in fact connected to one another
in a fluid way,
in the same way that there is really only one ocean on the planet,
and that what we for convenience call the Atlantic Ocean and Pacific Ocean et cetera,
to suit our needs for navigation and orientation,
are in fact one connected mass of water.

In the same way that we divide up the ocean for our convenience of understanding place,
taxonomy draws artificial lines across continuums of interconnectedness between genetically interchanging populations,
and creates categories meant to guide human understanding of the diversity of life forms.

Nature has no concern
nor regard
for the artificial taxonomic devices of human kind.
Nature gets on with what it does,
and is,
in all of its myriad forms of life.

Posted on July 6, 2023 02:31 PM by mjpapay mjpapay
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